General Arguments Against Ethical Naturalism
Total Page:16
File Type:pdf, Size:1020Kb
1 General Arguments against Ethical Naturalism Lewis Jed Brooks Department of Philosophy A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy Submission Date: November 2019. 2 3 Acknowledgements I cannot really believe that I have finally finished this thesis. Thanks are due to my supervisors Jimmy Lenman and Yonatan Shemmer. Their advice, support and feedback has been extremely helpful and it is much appreciated. I am also grateful to many other members, both past and present, of the University of Sheffield’s philosophy department. I will not mention many names for fear of forgetting to mention people I ought to, but particular thanks must go to Graham Bex- Priestly, Stephen Ingram, Miklos Kurthy, Alex Duval, James Lewis and Emma Bolton who were excellent sounding boards when I needed to run an embryonic or inchoate idea past them. I received financial support from the Arts and Humanities Research Council and training from the White Rose College of the Arts and Humanities; I am very grateful to both of these organisations for all they have done for me. Finally, I would like to thank my mum Carol and my partner Sophie without whose support I would not have been able to write this thesis. 4 Abstract Ethical naturalists argue that normative properties are, in some sense, nothing over and above natural properties. Some philosophers think that all forms of naturalism must fail. They present, what Jonathan Dancy calls, ‘Blockbuster arguments’, which they think rule out every kind of naturalism. In this thesis I argue that these arguments do not succeed. In the first two chapters, I argue that both analytic and synthetic naturalists have good responses to G.E. Moore’s open question argument. Derek Parfit, as well as other non-naturalists, have presented a number of supposedly separate arguments against naturalism which are not meant to rely on any considerations about meaning; I argue against these in chapters 3 and 4. Non-cognitivists argue that all descriptivist theories like naturalism fail to explain the necessary connection between normative judgements and motivation. I argue, in an oblique way, that the kind of motivational internalism needed to ground this argument is not a threat to naturalism in chapter 5. In chapter 6, I turn to what I take to be more serious problems for naturalists arising from Terry Horgan and Mark Timmons’ Moral Twin Earth thought experiments. I argue first that tackling these thought experiments is a problem that all major metaethical theories share. The fact that everyone needs to address these problems makes more palatable the responses I then go on to develop. First, I argue that we might be able to accommodate these cases if we accept that people can disagree even if the semantic content of their utterances are not logically inconsistent. Second, I argue that we can debunk the intuitions that Moral Twin Earth cases are supposed to pump. I end by summarising what I have argued in the thesis. 5 Declaration I, Lewis Brooks, confirm that the Thesis is my own work. I am aware of the University’s Guidance on the Use of Unfair Means (www.sheffield.ac.uk/ssid/unfair-means). This work has not been previously been presented for an award at this, or any other, university. 6 List of contents Acknowledgements 3 Abstract 4 Declaration 5 List of Contents 6 Introduction 7 Chapter 1 – The Open Question Argument: Part 1 11 Chapter 2 – The Open Question Argument: Part 2 48 Chapter 3 – The Normativity Argument 85 Chapter 4 – The Triviality Argument 115 Chapter 5 – The Argument from Motivational Internalism 144 Chapter 6 – The Moral Twin Earth Argument 188 Conclusion 222 References 224 7 Introduction A central metaethical question concerns the nature of normative properties. There is no easy way to define normativity and there is disagreement among philosophers over just which properties are the normative ones. For instance, some philosophers think that semantic properties like a word’s meaning are normative.1 Other philosophers think that being in a particular mental state, e.g. having a belief that P, is a normative matter.2 I sidestep these issues by focusing primarily on paradigmatically normative properties such as moral and prudential properties like goodness, badness, rightness, wrongness, etc. I defend a naturalist view of normative properties against some influential arguments found in the metaethics literature. Following David Enoch, I will understand ethical naturalism as the view that normative properties are, in a sense, nothing over-and-above natural properties.3 This characterisation is deliberately vague because I wish, for the most part, to remain neutral over whether the naturalist should say that the relationship between normative and natural properties is one of identity, reduction, constitution, grounding, or something else.4 Most of the time I will simply say that naturalism’s central claim is that normative properties are identical to natural properties. I think that this claim can be defended against the objections I consider in this thesis, but if there is a better way to characterise naturalism then I would be happy to adopt it. This characterisation is also vague in that it does not make clear what it means for a property to be natural. This is a large and difficult topic which I will largely skirt around as well. The standard account is that natural properties are those properties which could play explanatory roles in the natural sciences and psychology, and perhaps also the social sciences.5 For instance, 1 Kripke (1982) is the locus classicus for this position. 2 e.g. Blackburn (1998, Appendix). 3 Enoch (2011, ch.5). Graham Oddy (2005, Ch.1) does the same. 4 I do discuss one way we could understand the relationship between normative and natural properties in chapter 1, but I do not rule out other ways that we could do this. 5 Moore (1993) is an early proponent of this account. 8 since an object’s mass will feature in the explanations of natural phenomena given by physicists, a property like, has a mass of 1kg, will count as a natural property on this account. I do not think that this will ultimately prove to be the best way to characterise natural properties. However, I also think that if ethical naturalism turns out to be true then normative properties will be among the properties that could figure in the natural and social sciences as well as psychology. Additionally, I think that the claim that normative properties are among the properties that figure in the natural and social sciences as well as psychology, is defensible against the arguments I am going to go on to consider. That being so, the standard account of what a natural property is will suffice for my purposes. At first blush, naturalism appears to have several advantages over rival theories. I will mention just two. First, naturalism promises to vindicate many of our ordinary normative judgements with appeal only to a purely naturalistic ontology. This is in contrast to robust realist views, which have it that normative properties are non-natural, sui generis and irreducibly normative.6 It is argued, rightly in my view, that such properties would be mysterious and objectionably ‘queer’.7 Relatedly, if normative properties are just natural properties then we might come to know that something is, say, morally right in the same kinds of ways that we learn which natural properties a thing has. This again contrasts with rival views, according to which we (sometimes) learn which normative properties a thing has using some kind of mysterious reasoning process or a special intuitive faculty.8 Second, naturalists have an easy time explaining why normative properties supervene on natural properties, or, why there could not be worlds which are the same in all natural respects but 6 David Enoch (2011) offers, in my view, the best recent defence of this view. 7 Mackie (1977, ch.1) is the locus classicus of this complaint. 8 I add ‘sometimes’ in parentheses because rival accounts can allow that much of the time we learn what normative properties a thing has derivatively, i.e. by making inferences based on our knowledge of the other normative properties we know the thing to have. There must, however, be some way for us detect at least certain normative properties non-derivatively on these views, otherwise the process of normative deliberation could never get started. That non-derivative normative deliberation could not be understood in purely naturalistic terms. 9 which are different in normative respects. This normative supervenience claim is almost universally accepted; it just seems obvious that there could not be a world which was identical in every single natural respect to ours but in which, say, it was morally permissible to torture people for fun.9 Since every set of properties trivially supervenes on any set of properties of which it is a subset, naturalists can easily explain why normative properties supervene on natural properties. Rival theories meanwhile must accept that supervenience is simply a brute metaphysical fact or, to quote Simon Blackburn, “an opaque, isolated, logical fact, for which no explanation can be proffered.”10 Naturalism appears to be a promising theory, but many philosophers think that there is little hope of its proving to be true. In my view, establishing that naturalism is the correct view would require that we identify just which natural properties are identical to which normative properties, in a way that is consistent with, and make good sense of, the kinds of things we do and say using normative terms and normative concepts. Some philosophers disagree. They think that it is not necessary to examine particular identifications of normative properties with natural properties, since we know in advance that normative properties could not be natural properties.